Dental laboratory casting ring insert means



arch E4, 1950 F. .1. FRORELLA DENTAL LABORATORY CASTING RING INSERT MEANS Filed May 15, 1947' Inventor Frank J. F iorella Patented Mar. 14, 1950 :1;-

UNITED STATES PATENT OFFICE I DENTAL LABORATORY CASTING RING INSERT MEANS The present invention relates to novel and improved insert means which is especially and properly adapted for use within the confines of a partial denture casting and inlay ring or,

equivalent form, and an investment or filler which is poured and allowed to harden in said ring; and, the principal object of the invention is to adequately strengthen and reinforce the investment, by way of said insert, at the end portions, which usually protrude and bulge beyond the open ends of the ring, whereby said end portions are sufficiently harnessed and controlled to satisfactorily overcome undue and un-.. desirable expansion of said investment.

A dental laboratory in making partial denture castings of gold and stainless steel, in which tube teeth later are secured, uses, as is common to the trade, an imperforate open-ended metal ring into which is placed a wax pattern of the partial to be cast. When the patternhas been placed in the ring, a casting investment is poured into the ring around the pattern while said ring is in the horizontal position. When the invested pattern in the ring has been sufliciently heated (between 1250 and 1500) for the casting opera- I proper expansion, usually causes a hyperexpam sion of the casting investment, so that the ends of the latter'bulge slightly beyond the open ends.

of the ring. The result of this is that the mold itself is enlarged slightly, is therefore imperfect vertically, and does not conform perfectly to the master model, The vertical dimensional changes.

taking place before the casting is completed causes a high occlusion with the tube teeth that are placed in the casting, and it is necessary to trim the cusp of the teeth down to compensate for this imperfection. The use of the vertical insert controls and equalizes the horizontal and vertical dimensional expansion evenly throughout the mold, thereby minimizing any occlusal rise that may occur.

In carrying out the principles of the instant invention and with a view toward satisfactorily perfecting gold and equivalent castings, having been produced as above indicated, I provide simple. and expedient devicesin the form of metal inserts, these being of open-work form and being imbedded in the investment atthe proper stage and functioning as suitable reinforcement stays.

In reducing to practice a preferred embodiment, the insert means. is of annular form, in general outline and conforms to the surrounding annular investment jacketing ring and the end portions coact with opposite open ends of the ring, whereby and despite the terrific heat applied, the expansion of the investment is equalized.

Another object of the invention is to simplify the dental technique of producing suitably perfected gold inlays and abutments and equivalent partial denture castings for, under ordinary circumstances procedures necessitate making two investments, the first one which is in the form of a thin coating, being placed around the pattern and allowed to set for about ten minutes, and the second investment being made to completely fill the ring with the second mix. It follows that, by using the improvedreinforcing inserts, constituting the subject'matter of. the instant invention, but one investment is necessary.

Other objects and advantages will become more readily apparent from the following description and the accompanying illustrative drawings.

In the drawings, wherein like numerals are employed to designate like parts throughout the,v

views:

Figure 1 is a perspective view of insert meansv constructed in accordance with the invention- Figure 3 is a group perspective view of sections which go to make up the complete insert;

Figure 4 is a view showing a casting machine bracket, crucible, wax pattern, reinforcing insert means and ring, the latter part appearing in phantom or dotted lines.

Referring first to Figure ,4 the letter A designates a casting machine bracket such as is used currently in centrifugal casting machines, B denotes a crucible, C denotes a pattern of wax, D denotes wax or equivalent sprues and these are shown as intervening between the wax pattern C and crucible B. The customary open ended casting ring is denoted at E, this being shown in dotted lines.

The invention comprises merely the insert means and this may be of sectional construction or unitary construction as shown for example by comparing Figure 1 with Figure 2.

Referring now to the drawings and particularly to the stay andzreinforcing means; partly" referred to.-as insert means, this is shown; as illustrated in Figure 3, as made up of a pair of duplicate companion half-sections 6 and I. These are brought together in abutting, relationship to provide an open-work fra'nre' which; look? ing at either end, is of a general annular form and therefore conforms to and fits withinthet confines of the surrounding ringlil.v Aseach section is thesame in construction a description of one will suffice for both. To this end; each section comprises semi-circular flat metal plates 3 .and .9..-l1aving apertures. I 0. ther.ei-n,..said .plates;

being, connected by; spaced stay rods H'. rigidly. secured at their lower.ends,-.as.at. IZQto thB lOWEI:

plate. (see Figure 3)l andsecured atltheir opposite equivalent ring lB-landlaypair of diametrically oppositestay rods. Ill The. ring ...or annulus. I5." is suitably apertured for effectiveness in. .action. as indicated at the. points l8.- In thisformpf the invention the. forming or. casting, ring is -de.-

noted by the numeral H9.

The, insert. sections are made. of stainless .steel and their dimensions depend;.of course, upon.

the size of the ring, The semi-circular. portions. of 'saidsections are placed inthe ring. whileit is in a horizontalposition, atthesame time the. pattern and'investment'are. placed in the ring;

When so placed the semi-circular portionsof'ltheinserts form and,complete..a..circle, flush with,

the side of'thecopen ringinto-which the molten. metal'is thrown. The two ringshapedportions.

of eachofthe inserts are then flusliwith the otherop'en side ofithe ring; Thus, despite the terrificv heat applied the expansion oftheinvestment' is equalized." Otherwise, the lackof' this reinforcement ofttimes. results. in. hyperex pansion and consequent vertical imperfection of the mold and casting.

Without these inserts it is. usually necessary to? make ttvo investments; The first one; which.

is: a: thin coating, .is'. placed around the: pattern: and. allowed to' set for about: ten minutes. and

then the second investment is made to completely, fillthering'with the second mix. With use-of these. inserts but one: investment" is: nec

essary..

By use of'the insertions it is'found that the" investment will. nothyperexpand or crack'even' though the investment is. heated to a point several hundred degrees over andabove thespecification .of the" investment used;

These inserts are particularly efficacious" in manufacture of the bi-lateral andother larger. palatal bar castings, where the coating'ofinvestinentis'thinner and is therefore more-prone to hyperexpand, crack, and cause imperfections. The control of the vertical dimensional expansion permits a greater degree of horizontal expansion which is necessary to prevent a cross arch bind.

A careful consideration of the foregoing description in conjunction with the invention as illustrated in the drawings will enable the reader towobtainaaclear understanding; and impression ofjtheialleged features ofmerit and novelty sufficient to clarify the construction of the invention as hereinafter claimed.

Minor changes in shape, size, materials and rearrangements 'ofparts may be resorted to in actualpractice so long as no departure is made from'theinvention as claimed.

Having. described the invention, what is claimed as-new'is'z l. Asia new article of manufacture, a dental laboratory casting ring insert of the class shown and. described comprising; a. pair of. duplicate half sections. adapted. to. assume opposed. posie Lions-in relation to eachpther and,.thus.combinect'to provide an open-workJframe-like. de-

vice, said half-sections. each including a pair offspaced semi-circular flatlmetal plates. and

rod memb'ersconnecting said plates inv spacedparallelism, theplat'es' of the respective halfsections being" disposed inv a planawith each other when in use .in said castingring,

21 Means for-use. ina dental laboratory by a dentisti'or "a. technician, to' aid'in dimensionally perfecting gold or chromium partial castings comprising;.a castingring insert. adapted to be placed in aconventi'ona'ltype open-ended'cylindricalcastingring, said insert being of 'a length corresponding'to the length of the ring andem, bodyingapair ofspaced parallel end frames substantially: flush with the respective .open ends. of ?said casting ring functioning to minimizevertica'ldimension'alexpansion of the" end portions of'th'e mold which is poured. in said'ring, and said endframes, comparedfito thediameter of said ring; being'relatively wide in cross section, each end *framebeing composed of opposed and aligned.

semi-circular'apertured plates, the complemental plates-- oftherespective end-frames being connected togetherby. rods, said'rods', compared to said plates,- being'relatively' small in cross-section andwidely spaced-from each other toallow for uniform horizontal expansion of the'molcl so as to effectively 'control' and equalizehorizontal .and

vertical dimensional expansion evenly throughout.

REFERENCES CITED The-following references. are of record. in: the file? of. this patent:v

UNITED STATES PATENTS Number Name Date l;444,060 Burns, Feb..6, 1923 1,545,061. Noyes 4. July 7, 1925 2,219,640 Summy, .Oct. 29, 1940- FOREIGN' (PATENTS Number Country Date 600,592 Germany .Jul 26, 1934' 

